DUMET Medical DUMET Medical Solved Paper-2001

  • question_answer
    The escape velocity of sphere of mass m from earths surface will be: (G = universal gravitational constant, \[{{M}_{e}}\]= mass of the earth,  \[{{R}_{e}}\] = radius of the earth)

    A) \[\sqrt{\frac{2G{{M}_{e}}+{{R}_{e}}}{{{R}_{e}}}}\]

    B) \[\sqrt{\frac{2G{{M}_{e}}m}{{{R}_{e}}}}\]

    C) \[\sqrt{\frac{2G{{M}_{e}}}{{{R}_{e}}}}\]

    D)  \[\frac{G{{M}_{e}}}{{{R}_{e}}}\]

    Correct Answer: C

    Solution :

    The work done to take a body of mass m where the earths attraction is negligible, is \[W=\frac{G{{M}_{e}}m}{{{R}_{e}}}\] This is equal to kinetic energy on surface of earth. i.e., \[\frac{1}{2}m{{v}_{e}}^{2}=\frac{G{{M}_{e}}m}{{{R}_{e}}}\] \[\Rightarrow \] \[{{v}_{e}}\sqrt{\frac{2G{{M}_{e}}}{{{R}_{e}}}}\]


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